Abstract: :
Purpose: To determine the ability of a newly developed spectrographicdigital fundus oxymeter to detect differences in oxygen tensionin retinal vessels induced by 100% oxygen breathing (hyperoxia).Methods: Thirteen healthy subjects (26.5 ± 3.8years)were evaluated before and after 100% oxygen breathing. Threemeasurements were obtained while breathing room air, focusingon the major temporal retinal vessels adjacent to the opticdisc. After five minutes of 100% oxygen breathing, two additionalmeasurements were taken. Oxygen breathing was maintained duringall measurements. The fundus was illuminated by white light,from which two frequencies were quantified: 605nm (oxygen sensitive)and 586nm (oxygen insensitive). After calibrating the imagesto optical densities, the optical density ratio (ODR) betweenoxygen sensitive and insensitive wavelengths was calculated.Baseline and hyperoxic ODR in the temporal arteries and veinswere compared by Wilcoxon signed rank paired comparisons (p<0.05 = statistical significance).Results: Hyperoxia significantlyincreased venous ODR by 9.4% (p = 0.009). Venous oxygen tensionwas significantly less than arterial oxygen tension at baseline(p=0.04). Hyperoxia eliminated this difference.Conclusion:It is possible to measure changes in arterial and venous oxygentensions in the human eye with the spectrographic digital fundusoxymeter. The ability to measure oxygen extraction by the neuroretinalrim and retinal tissue with this instrument will open up newhorizons of research into the vascular pathophysiology of glaucomaand other ocular diseases.